Patent GB-1412673-A (GB)
Title: Telecommunication exchange
IPC: H04Q3/54
Filed: 1973-02-02
Abstract: 1412673 Automatic exchange systems PLESSEY CO Ltd 20 Dec 1973 [2 Feb 1973] 5319/73 Heading H4K A TXE 2 exchange (shown in solid lines) is modified to handle more efficiently incoming junction calls by the addition of extra registers r, each having a calling number store, Sg and a called number store Sd, an extra register finder f, an extra call control equipment c and an extra calling number generator g. In a standard TXE2 exchange registers R are available for storing the calling (SG) and called (SD) numbers for both own-exchange and junction calls. To reduce the dangers of blocking, the extra equipment shown in chain-dotted lines is added for dealing with incoming junction calls. With this extra equipment leads 1, 3, 8, 12, the stores J and the connection between lead 6 and the junction side DJ of a decoder D become redundant. Setting up a call.-When the additional apparatus is provided, the lead 1 from the incoming supervisory set I is diverted to the additional calling number generator g as shown at 21. The generator g therefore is used only for incoming calls, and generates only numbers which are allocated to junctions. Operation of the generator g causes one of the additional registers r to be assigned to the call; and the generated number is written into the calling store sg of the assigned register over lead 22. When the calling number is stored in the store sg, the register delivers a demand signal to the additional register-finder f over lead 24. The additional finder f is tied to the additional call control equipment c. When the equipment c is free, the finder f finds the demanding register, and connects the equipment c thereto over lead 25, causing the store sg to be read. The number read from the store sg is delivered to the junction side DJ of the decoder D over lead 26. The decoder D decodes the number and transmits a signal over lead 7 to the incoming supervisory set I, as a result of which a connection is established between the set I and the assigned register over leads 28, 29 and one of the additional access switches a. The equipment c is released. Dial pulses are now received over the junction and are passed by means of the connection over leads 28, 29 to the called store sd of the register. When the called number is stored, the register develops a demand signal. This signal is delivered over lead 34 to the main register-finder F which is tied to the main call control equipment C. When the main equipment C is free, the main finder F finds the demanding register, and connects the main equipment C thereto over lead 35, causing the store sd of the demanding register to be read. The number read from the store ad is passed over lead 36 to the subscriber side DS of the decoder D. The called line is identified over lead 10, and the main call control equipment C is effective, by means of the connection 11, to set up the requisite speech path in the switching network S. When the speech path has been set up, the call control equipment C and the register rare released. Tandem traffic.-A switching network s, additional to the main network S, is provided for switching calls from incoming junctions, terminating on supervisories I, to outgoing junctions, beginning on supervisories o. In this case the called stores sd of the registers r are adjusted in accordance with the codes allocated to the outgoing routes, so that a preparatory signal is delivered to the register finder f. A tandem call is dealt with as an incoming call until a preparatory signal is developed. This causes the signal from the called store sd to be decoded by the routing equipment re instead of by D. The equipment c then controls establishment of a path through the network S between marked supervisories I and o.